1. Field of the Invention
The present invention relates generally to cutting instruments for nasal surgery and in particular to an instrument for cutting septal cartilage in operations such as submucous resections and rhinoplasty.
2. Description of the Prior Art
It is often desirable to perform an operation which involves cutting the nasal septum, that is, the septal cartilage which separates the two passages of the nose. For example, when a person with a broken nose has a deviated septum that blocks breathing in one of his nasal passages, a submucous resection is commonly performed in which a portion of the septal cartilage blocking his breathing is cut out. The septal cartilage is also cut in rhinoplasty, that is, cosmetic surgery performed to remove a hump from the nose.
One of the major difficulties in performing operations on the septal cartilage is the limited access which the nostrils and the nasal passages provide to the nasal septum. The nostrils are relatively small openings and the nasal passages are narros compared to their depth. The cutting instruments which have been used in the prior art for nasal surgery usually involve a relatively straight handle which holds a cutting edge that extends in the direction of the handle or at a relatively slight angle to it. Because of the orientation of the cutting surfaces on such instruments, it is difficult for them to enter a nasal passage and made a cut across the width of the nasal cartilage, without temporarity deforming the nostrils and the nose, particularly in portions of the cartilage far removed from the nostrils. In addition, the orientation of the cutting surfaces in such instruments often makes such cutting surfaces hard to see when they are cutting in the nose, because such cutting surfaces tend to be obscured by the handles to which they are attached.
The difficulties associated with such blades have caused the rather primative swivel knife to be commonly used in submucous resections. The swivel knife has a blade extended between two prongs attached to its handle. The blade swivels so that the angle in which it cuts can rotate about its axis between the two prongs. In a submucous resection using the swivel knife, the lower end of the nasal septum is separated from the columnella, the flesh separating the two nostrils. The mucous membranes on both sides of the septum are separated from the septum, and the collumnella is bent to one side to expose the lower end of the septum. The blade of the swivel knife is placed against the exposed end of the septum with the mucous membranes placed outside the knife's two prongs. Then the blade is moved in a generally circular motion to cut out a section of the septal cartilage. The swivel knife is a primative tool because it is difficult to accurately control its cutting motion, and its two prongs make it difficult to see what it is cutting.